Portable machine tools such as semi-automatic, portable drills are commonly used throughout industry for performing machining operations on workpieces. For example, portable drills are extensively used in the aircraft industry to produce countersunk holes that receive rivets attaching an outer skin to frame members. The drill is carried on a portable fixture that includes a clamp for clamping the fixture onto a workpiece so that the drill is held in a precise, fixed position throughout a drilling operation. The drill body is mounted on a slide on the fixture to allow a cutting tool such as a countersink drill bit to be fed in a drill stroke between a retracted position and a cutting position in which the drill bit engages the desired location on the workpiece.
During the drilling process, workpiece chips and/or dust is generated between the cutter and workpiece hole surface interface. The chips/dust not only reduce the quality of the hole, but also increase cutter wear and reduce cutter life. The dust generated during drilling of carbon fiber composites is particularly problematic because it functions as a “grinding material” at the cutter/workpiece interface, reducing hole quality and causing rapid cutter wear. Moreover, the carbon fiber dust can become an airborne hazard or contaminate that settles on factory floors and equipment, necessitating cleanup operations. It is therefore particularly important to quickly remove and contain the chips and dust as they are generated by the drilling operation.
In the past, automated drilling/fastening systems have employed directed air pressure to blow chips away from the drilling area, however this technique disperses the chips and dust into the air, resulting in potential airborne hazards and necessitating cleanup operations. In order to prevent carbon fiber dust from becoming airborne, it has been purposed to submerse the workpiece in a liquid such as water in order to trap the carbon dust. However this technique results in a water/dust emulsion which requires special treatment, handling and disposal. In some cases, the water seeps into gaps in the workpiece and must be removed prior to fastener installation.
From the forgoing, it can be appreciated that previous techniques used for removing chip debris and dust have not been completely effective, and/or have required secondary clean-up operations. Accordingly, there is a need for a debris removal system that overcomes these problems. The present invention is directed towards satisfying this need.